Identification of genes or polypeptides the expression of which correlates to fertility, ovarian function and/or fetal/newborn viability

ABSTRACT

A genetic means of determining whether a female subject produces “pregnancy competent” oocytes is provided. The means comprises detecting the level of expression of one or more genes that are expressed at characteristic levels (upregulated or downregulated) in cumulus cells derived from pregnancy competent oocytes. This characteristic gene expression level, or pattern referred to herein as the “pregnancy signature”, also can be used to identify subjects with underlying conditions that impair or prevent the development of a viable pregnancy, e.g., pre-menopausal condition, other hormonal dysfunction, ovarian dysfunction, ovarian cyst, cancer or other cell proliferation disorder, autoimmune disease and the like. Microarrays containing “pregnancy signature” genes or corresponding polypeptides provide another preferred aspect of the invention. Still further, the subject invention can be used to derive animal models, e.g., non-human primate animal models, for the evaluation of the efficacy of putative female fertility treatments.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of U.S. Ser. No. 11/ 437,797filed on May 22, 2006, which is in turn a continuation-in-part of U.S.Ser. No. 11/091,883 filed on Mar. 29, 2005. This application furtherclaims the benefit of provisional application No. 60/556,875 filed Mar.29, 2004. All of these applications are incorporated herein by referencein their entirety.

FIELD OF THE INVENTION

The present invention provides genetic methods that provide for theidentification of “pregnancy competent” oocytes, i.e., oocytes that whenfertilized and transferred to a suitable uterine environment are capableof yielding a viable pregnancy. The present invention further providesgenetic methods of identifying female subjects, preferably human femaleshaving impaired fertility function, e.g., as a result of impairedovarian function, e.g., as a result of age (menopause) or an underlyingdisease condition or therapy.

Also, the invention provides methods of evaluating the efficacy of aputative fertility treatment based on its effect on the expression ofspecific genes.

Further, the invention identifies genes which are differentiallyexpressed by cumulus cells that correlate to the pregnancy potential ofoocytes that are associated therewith.

Further, the present invention provides an improved mRNA amplificationprotocol that is especially suited for gene expression profiling ofbiological samples of small quantity, such as cumulus or stem cellcontaining cell samples.

BACKGROUND OF THE INVENTION

Currently, there is no available genetic procedures for identifyingwhether a female subject produces oocytes that are “pregnancycompetent”, i.e., oocytes which when fertilized by natural or artificialmeans are capable of giving rise to embryos that in turn are capable ofyielding viable offspring when transferred to an appropriate uterineenvironment. Rather, conventional fertility assessment methods assessfertility e.g., based on hormonal levels, visual inspection of numbersand quality of oocytes, surgical or non-invasive (MRI) inspection of thefemale reproduction system organs, and the like. Often, when a woman hasa problem in producing a viable pregnancy after a prolonged duration,e.g., more than a year, the diagnosis may be an “unexplained” fertilityproblem and the woman advised to simply keep trying or to seek otheroptions, e.g., adoption or surrogacy. Therefore, providing alternativeand more predictive methods for identifying women with fertilityproblems would be highly desirable. Likewise, novel and improved methodsfor treating fertility problems would be highly desirable.

Still further, the identification of women with fertility problems,preferably earlier on than by current methods is desirable, as fertilityproblems may correlate to other health issues that preclude pregnancy,e.g., cancer, menopausal condition, hormonal dysfunction, ovarian cyst,or other underlying disease or health related problems.

BRIEF DESCRIPTION AND OBJECTS OF THE INVENTION

It is an object of the invention to provide a novel and improved methodof detecting infertility problems and the genetic basis thereof.

It is a more specific object of the invention to provide a novel methodof detecting female fertility or infertility which method comprisesevaluating the capability of oocytes produced by said female topotentially give rise to a viable pregnancy upon fertilization andtransferral into a suitable uterine environment, wherein said methodinvolves detecting the levels of expression of specific (“pregnancysignature”) genes or polypeptides encoded thereby by cells that areoocye-associated, e,g., cumulus cells.

It is another specific object of the invention to provide a method ofevaluating whether a subject produces oocytes capable of giving rise toa viable pregnancy comprising:

(i) measuring the expression levels of genes in a oocyto-associatedcell, e.g., a cumulus cell, wherein said genes are expressed or notexpressed at characteristic levels (“pregnancy signature”) in cellsassociated with oocytes capable of yielding a viable pregnancy; and

(ii) detecting the “pregnancy potential” of said oocytes based on thelevel of similarity of said gene expression pattern to said “pregnancysignature”.

It is another specific object of the invention to identify a femalesubject putatively having a condition that inhibits or preventspregnancy by detecting whether said subject produces oocytes associatedwith cells, e.g., cumulus cells, which do not express one or more genesin a manner characteristic of “pregnancy competent” oocytes; whereinsaid method comprises detecting the expression of said one or more“pregnancy signature” genes in at least one cell associated with anoocyte isolated from said female subject; and thereby identifying thesubject as potentially having a health problem which prevents orprecludes fertility based on an abnormal expression pattern of at leastone of said “pregnancy signature” genes.

It is another object of the invention to provide a method of evaluatingthe efficacy of a female fertility treatment which comprises:

(i) treating a female subject putatively having a problem that preventsor inhibits her from having a “viable pregnancy” and

(ii) isolating at least one oocyte from said female subject and cellsassociated therewith after said fertility treatment;

(iii) isolating at least one cell associated with said isolated oocyte,preferably a cumulus cell, and detecting the level of expression of atleast one gene that is expressed at a characteristic level of expressionin “pregnancy competent” oocytes; and

(iv) determining the putative efficacy of said fertility treatment basedon whether said gene is expressed at a level characteristic of“pregnancy competent” oocytes as a result of treatment.

It is another object of the invention to provide animal models forevaluating the efficacy of putative fertility treatments comprisingidentifying genes which are expressed at characteristic levels incumulus cells associated with pregnancy competent oocytes of a non-humananimal, e.g., a non-human primate; and assessing the efficacy of aputative fertility treatment in said non-human animal based on itseffect on said gene expression levels, i.e., whether said treatmentresults in said gene expression levels better mimicking gene expressionlevels observed in cumulus cells associated with pregnancy competentoocytes, (“pregnancy signature”).

It is another object of the invention to identify specific human genesthat are differentially expressed by cumulus cells and otheroocyte-associated cells and to assay the expression of one or more ofsuch specific genes by cumulus or other oocyte-associated cells as anindicator of fertility and ovarian function.

It is another object of the invention to provide a novel mRNAamplication protocol especially suited for biological samples of smallquantity that combines the use of specific primers, i.e., SMART IIoligonucleotide (Clontech, CA) and T7-oloigo(dT)24V promoter primers(Ambion, Tex.).

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A-1C and 1D-1I depict schematically a genetic fertility testingmethod according to the invention. FIG. 1A shows a freshly ovulated eggcontaining a polar body, zona pellucida and cumulus cells. FIG. 1B showsthe fertilization and transferral of this egg into a uterineenvironment. FIG. 1C shows the recovery of cumulus cells from theoocytes shown in 1A which are to be used for genetic testing. FIG. 1D-1Ishow the isolation of RNAs from said cumulus cells, microarray analysisof said RNAs, validation of 100 genes by real time RT-PCR, correlationof the levels of expression of said genes (upregulated or downregulated)to the ability of an oocyte to give rise to a viable pregnancy, and theuse of this gene expression profile to identify a set of genes, theexpression of which correlates to the capability of an oocyte to yield aviable pregnancy (“pregnancy signature”)

FIG. 2 contains a flow chart of the CRL amplification protocol used inthe present invention.

FIG. 3 contains a digital RNA gel-like image of total RNA sampleisolated from 8 mature oocytes run 3 times.

FIG. 4 contains RT-PCR verification of GeneChip array results forsamples as described infra.

FIG. 5 contains selected overrepresented GO biological processes inoocytes identified by EASE.

FIG. 6 contains Venn diagrams depicting intersection of differentiallyexpressed genes in human and mouse oocytes and ESCs.

FIG. 7 contains primers and sequences used to validate RT-PCR microarrayexperimental results.

FIG. 8 contains selected representations of genes common to human andmouseoocytes with homologs functionally characterized in the mouse oocye(16 genes out of top 100 genes).

FIG. 9 contains 66 unique genes in common between human oocytes, mouseoocytes, hESCs, and mESCs.

FIG. 10 contains genes differentially expressed in human oocytescorresponding to TGF-beta signaling pathway.

FIG. 11 contains gene that are differentially expressed in human andmouse oocytes that are in the estrogen receptor signaling pathway.

FIG. 12 contains progeny distribution of 27 analyzed in vitrofertilization (IVF) patients.

FIG. 13 contains a detailed flow chart describing the steps of theinvention starting from the IVF clinic to the gene expression results.Panel A illustrates a sample collection from freshly ovulated maturecumulus-oocyte complex in vivo. Panel B shows quality and quantitychecking of total RNA from 4 different cumulus cell lysates.

FIG. 14 depicts schematically the experimental design of the protocol inmore detail than FIG. 1.

FIG. 15 contains a summary of CRL RNA amplification protocol describedherein. Panel B shows the means of validating amplication fidelity.

FIG. 16 shows clustering of samples using genes that are called presenton 4 pregnant and 4 non-pregnant donor samples (442 probe sets).

FIG. 17 contains experimental patterns of 3 candidate pregnancy markersin cumulus cells that resulted in pregnancy versus no pregnancy.

FIG. 18 contains a Table containing the top 10 functional categoriesoverreported in differentially expressed genes between cumulus cellscoming from oocytes that produce progeny and those that fail to produceprogeny. Gene orthology biological properties and molecular function asdetected by EASE when oocyte expressed genes were compared to the genesrepresented in the GeneChip array.

FIG. 19 contains the sequences of three differentially expressed genesin FIG. 17 that are expressed on average at substantially elevatedamounts in cumulus cells derived from occytes that give rise to progenyversus those which do not.

DETAILED DESCRIPTION OF THE INVENTION

Prior to discussing the invention in more detail, the followingdefinitions are provided. Otherwise all words and phrases in thisapplication are to be construed by their ordinary meaning, as they wouldbe interpreted by an ordinary skilled artisan within the context of theinvention.

“Pregnancy-competent oocytes”: refers to a female gamete or egg thatwhen fertilized by natural or artificial means is capable of yielding aviable pregnancy when it is comprised in a suitable uterine environment.

“Viable-pregnancy”: refers to the development of a fertilized oocytewhen contained in a suitable uterine environment and its developmentinto a viable fetus, which in turn develops into a viable offspringabsent a procedure or event that terminates said pregnancy.

“Cumulus cell” refers to a cell comprised in a mass of cells thatsurrounds an oocyte. This is an example of an “oocyte associated cell”.These cells are believed to be involved in providing an oocyte some ofits nutritional and or other requirements that are necessary to yield anoocyte which upon fertilization is “pregnancy competent”.

“Differential gene expression” refer to genes the expression of whichvaries within a tissue of interest; herein preferably a cell from anoocyte, e.g., a cumulus cell.

“Real Time RT-PCR”: refers to a method or device used therein thatallows for the simultaneous amplification and quantification of specificRNA transcripts in a sample.

“Microarray analysis”: refers to the quantification of the expressionlevels of specific genes in a particular sample, e.g., tissue or cellsample.

“Pregnancy signature”: refers to a phrase coined by the inventors whichrefers to the characteristics levels of expression of a set of one ormore genes, preferably at least 5, more preferably at least 10 to 20genes, and still more preferably, at least 50 to 100 genes, that areexpressed at characteristic levels in oocyte cells, preferably cumuluscells, that surround “pregnancy competent” oocytes. This is intended toencompass the level at which the gene is expressed and the distributionof gene expression within cells analyzed.

“Pregnancy signature gene”: refers to a gene which is expressed atcharacteristic levels by a cell, e.g., cumulus cell, on a “pregnancycompetent” oocyte.

“IVF”: refers to in vitro fertilization.

“Zona pellucida” refers to the outermost region of an oocyte.

“Method for detecting differential expressed genes” encompasses anyknown method for evaluating differential gene expression. Examplesinclude indexing differential display reverse transcription polymorasechain reaction (DDRT-PCR; Mahadeva et al, 1998, J. Mol. Biol.284:1391-1318; WO 94/01582; subtractive mRNA hybridization (See AdvancedMol. Biol.; R. M. Twyman (1999) Bios Scientific Publishers, Oxford, p.334, the use of nucleic acid arrays or microarrays (see Nature Genetics,1999, vol. 21, Suppl. 1061) and the serial analysis of gene expression.(SAGE) See e.g., Valculesev et al, Science (1995) 270:484-487) and realtime PCR (RT-PCR). For example, differential levels of a transcribedgene in an oocyte cell can be detected by use of Northern blotting,and/or RT-PCR.

CRL amplification protocol refers to the novel total RNA amplificationprotocol depicted schematically in FIG. 2 that combinestemplate-switching PCR and T7 based amplification methods. As notedabove, this protocol is well suited for samples wherein only a few cellsor limited total RNA is available.

Preferably, the “pregnancy signature” genes will be detected byhybridization of RNA or DNA to DNA chips, e.g., filter arrays comprisingcDNA sequences or glass chips containing cDNA or in situ synthesizedoligonucleotide sequences. Filtered arrays are typically better for highand medium abundance genes DNA chips can detect low abundance genes. Inthe exemplary embodiment the sample may be probed with AffymetrixGeneChips comprising genes from the human genome or a subset thereof.

Alternatively, polypeptide arrays comprising the polypeptides encoded bypregnancy signature genes or antibodies that bind thereto may beproduced and used for detection and diagnosis.

“EASE” is a gene ontology protocol that from a list of genes formssubgroups based on functional categories assigned to each gene based onthe probability of seeing the number of subgroup genes within a categorygiven the frequency of genes from that category appearing on themicroarray.

As noted above, the present invention preferably provides a novel methodof detecting whether a female subject, human or non-human, produces“pregnancy competent” oocytes. The method involves detecting the levelsof expression of one or more genes that are expressed or not expressedat characteristic levels by cumulus cells associated with (surrounding)oocytes that are “pregnancy competent”, i.e., which when fertilized bynatural or artificial means (IVF), and transferred into a suitableuterine environment are capable of yielding a viable pregnancy, i.e.,embryo that develops into a viable fetus and eventually an offspringunless the pregnancy is terminated by some event or procedure, e.g., asurgical or hormonal intervention.

The invention further provides a novel and improved means for amplyingthe total RNA from a particular cell sample that combinestemplate-switching PCR and T7-based amplification methods (referred toherein as CRL amplification protocol). While this method is preferablyused for assaying gene expression by oocyte, cumulus, or ES total RNAsamples it is applicable for any cell sample, preferably a cell samplewherein amplifiable RNA is only available in small quantity.

The invention further provides transcriptome data obtained from oocyte,cumulus, or ES cells that identifies genes which are differentiallyexpressed therein.

The invention in particular identifies 1626 genes that aredifferentially expressed by human ES cells.

The invention further identifies 5331 transcripts upregulated and 7074transcripts down-regulated in human oocyte sample. Upregulated genesinclude FIGLA, STELLA, VASA, DAZL, GDF9, ZP1, ZP2, MOS, OCT4, NPM2, andH1FOO.

The invention further compares transcriptomes from human and mouseoocytes and identifies 1587 genes common (differentially expressed) toboth.

The invention further compares the transcriptomes of oocytes and EScella and identifies 388 (human) and 591 (mouse)genes differentiallyexpressed in both as well as a set of 66 genes that are preferentiallydifferentially expressed in each of human and mouse ESCs and oocytes.

In particular the invention provides a comprehensive expression baselineof gene transcripts present in in vivo matured metaphase II humanoocytes.

In preferred embodiments, the inventive methods will be used to identifywomen subjects who produce or do not produce pregnancy competent oocytesbased on the levels of expression of a set of differentially expressedgenes. However, the inventive methods are applicable to non-humananimals as well, e.g., other mammals, avians, amphibians, reptiles, etal. For example, the subject invention may be used to derive animalmodels for the study of putative female fertility treatments.

Additionally, the present invention may be used to identify femalesubjects who have an abnormality that precludes or inhibits theirability to produce pregnancy competent oocytes, e.g., ovariandysfunction, ovarian cyst, pre-menopausal or menopausal condition,cancer, autoimmune disorder, hormonal dysfunction, cell proliferationdisorder, or another health condition that inhibits or precludes thedevelopment of pregnancy competent oocytes.

For example, subjects who do not express specific pregnancy signaturegenes at characteristic expression levels will be screened to assesswhether they have an underlying health condition that precludes themfrom producing pregnancy competent oocytes. Particularly, such subjectswill be screened to assess whether they are exhibiting signs ofmenopause, whether they have a cancer, autoimmune disease or ovarianabnormality, e.g., ovarian cyst, or whether they have another healthcondition, e.g., hormonal disorder, allergic disorder, etc., that maypreclude the development of “pregnancy competent” oocytes.

Additionally, the subject methods may be used to assess the efficacy ofputative female fertility treatments in humans or non-human femalesubjects. Essentially, such methods will comprise treating a femalesubject, preferably a woman, with a putative fertility enhancingtreatment, isolating at least one oocyte and associated surroundingcells from said woman after treatment, optionally further isolating atleast one oocyte and associated surrounding cells prior to treatment,isolating at one cumulus cell from each of said isolated oocytes;detecting the levels of expression of at least one gene that isexpressed or not expressed at characteristic levels by cumulus cellsthat are associated with (surround) pregnancy competent oocytes; andassessing the efficacy of said putative fertility treatment based onwhether it results in cumulus cells that express at least one pregnancysignature gene at levels more characteristic of cumulus cells thatsurround pregnancy competent oocytes (than without treatment). As noted,while female human subjects are preferred, the subject methods may beused to assess the efficacy of putative fertility treatments innon-human female animals, e.g., female non-human primates or othersuitable animal models for the evaluation of putative human fertilitytreatments.

Still further, the present invention may be used to enhance the efficacyof in vitro or in vivo fertility treatments. Particularly, oocytes thatare found to be “pregnancy incompetent”, or are immature, may becultured in a medium containing one or more gene products that areencoded by genes identified as being “pregnancy signature” genes, e.g.,hormones, growth factors, differentiation factors, and the like, priorto, during, or after in vivo, or in vitro fertilization. Essentially,the presence of these gene products should supplement for a deficiencyin nutritional gene products that are ordinarily expressed by cumuluscells that surround “pregnancy competent” oocytes, and which normallynurture oocytes and thereby facilitate the capability of these oocytesto yield viable pregnancies upon fertilization.

Alternatively, one or more gene products encoded by said pregnancysignature genes may be administered to a subject who is discovered notto produce pregnancy competent oocytes according to the methods of theinvention. Such administration may be parenteral, e.g., by intravenous,intramuscular, subcutaneous injection or by oral or transdermaladministration. Alternatively, these gene products may be administeredlocally to a target site, e.g., a female ovarian or uterine environment.For example, a female subject may have her uterus or ovary implantedwith a drug delivery device that provides for the sustained delivery ofone or more gene products encoded by “pregnancy signature” genes.

Also, the novel CRL amplication protocol of the invention may be used toidentify differentially expressed genes from any cell sample, preferablythose only available in limited numbers such as e.g., samples used inforensic analysis, pathological samples such as cancer cells, especiallycancer stem cells, cell samples suspected of containing an unknownpathogen, cell samples obtained from cells undergoing specific cellularprocesses such as differentiation, apoptosis, angiogenesis, and thelike. This protocol has been found to faithfully and consistentlyamplify small amounts of RNA to quantities required for microarrayanalysis.

Thus, in general, the present invention involves the identification andcharacterization, in terms of gene identity and relative abundance, ofgenes that are expressed by desired cells, e.g., cumulus cells derivedfrom an egg, preferably human egg, at the time of ovulation, preferablycumulus cells, the expression levels of which correlate to thecapability of said egg to give rise to a viable pregnancy upon naturalor artificial fertilization and transferal to a suitable uterineenvironment. Also, the invention identifies a set of genesdifferentially expressed by human or murine ESCs and metaphase IIoocytes.

In one preferred embodiment, of the invention at least 50 to 100 genesthat are significantly upregulated or downregulated, by cumulus cellsthat correlate to the “pregnancy competency” of an oocyte from whichsaid cumulus cells are associated with will be chosen and monitored inthe inventive genetic testing methods.

However, while the invention preferably will select at least 50-100genes from each of said categories, it is anticipated that the inventivemethods alternatively may be practiced by monitoring the expressionlevels of fewer numbers of cumulus cell expressed genes, wherein saidgenes are similarly selected to be those which correlate to cumuluscells associated with “pregnancy competent” oocytes, i.e., those thatare capable of yielding viable pregnancies.

According to the invention, gene expression levels will preferably bedetected by the novel CRL amplification protocol provided herein.However other known methods, preferably real time detection methods suchas mentioned above may be used to detect and quantify gene expression.Methods for detecting relative gene expression levels are known in theart and well within the purview of the ordinary skilled artisan.

As noted supra, this invention further provides a novel mRNA amplicationprotocol that is well suited for small cell samples such as thosecontaining only a few or even a single cumulus cell or oocyte or ESC orother desired cells. This amplification protocol is well suited as wellfor forensic applications where only a minute nucleic acid sample may beavailable. Also, this technique is useful wherein only a few cells maybe isolated from an individual such as adult stem cells, cancer stemcells, other differentiation specific cells, olfactory cells, tastecells, and the like. The present protocol will be useful in thebiomedical field such as by medical and veterinary pathologists, e.g. incoordination with Laser-assisted Microdissection of tissues.Particularly, such applications may include cancer-related applications,research and disease diagnosis.

Previously, in order to generate a biotin-labeled antisense aRNA targetfor GeneChip experiments from limited amount of RNA samples, thisentailed the use of commercial kits e.g., those available from a fewvenders (such as Ambion TX, and Arcturus, CA). All of these kits use thesame approach based on the Eberwine T7 amplification method (SeeEberwine Biotechniques 20:584-591 (1996)).

By contrast, the present invention provides an improvement thereoverthat faithfully and consistently amplifies small amounts of RNA toquantities required to perform microarray experiments. The CRLamplification protocol disclosed herein provides a practical approach tofacilitate the analysis of gene expression in samples of small quantitywhile maintaining the relative gene expression profile throughoutreactions (Kocabas et al., “Transcriptome Analysis of the Human Ooocyte”In Press, 2006).

This amplification protocols achieves at least the following advantagesversus available protocols:

(i) global mRNA amplification is possible for a limited number of cells,tissues and micro-dissected biopsy using other (non-CRL) PCRamplification method;

(ii) the protocol is comprised of simple laboratory manipulations;

(iii) the simplicity of the protocol contributes to a high level ofreproducibility from experiment to experiment; and

(iv) the protocol time is shorter than other methods, in particular whenmultiple rounds are performed.

Based on these advantages this methodology is well suited for use in thepresent differential gene expression based-assays which detect genes theexpression of which correlates to oocytes or embryonic stem cells aswell as other applications wherein the detection of expressed genes in asample is desired.

Essentially, the CRL protocol is depicted in FIG. 2 and comprises (i)first strand cDNA synthesis coupled with dC tailing by MMLV RT (RnaseH-); (ii) template switching and chain extension by RT; (iii)amplification of cDNA a requisite number of cycles, typically 5 to 50,more preferably around 10-20, more preferably around 15 cycles by LD-PCRusing SMART primers; (iv) and production of double stranded DNAs by invitro transcription using T7 RNA polymerase. As noted this methodologyis applicable for amplification of mRNAs in any sample, but preferablyis used in amplifying mRNAs from relatively small cell samples such assamples containing a few number of cumulus cells, oocytes, or stemcells.

In the inventive pregnancy signature gene detection methods, cumuluscells will be isolated from oocytes of different female subjects, theoocytes fertilized by known IVF procedures, and the cumulus cells of thecorresponding isolated oocytes being subjected to gene expressionanalysis, i.e., by isolation of total RNA therefrom, amplification ofsaid total RNA, quantification of the relative gene expression levels ofsaid RNAs by microarray analysis and RT-PCR, and the identification ofgenes, the expression of which correlates to oocytes that give rise to aviable pregnancy.

To effect such identification, as a separate step, the status of embryosfertilized with oocytes derived from each of said cumulus cell sampleswill be monitored and pregnancy data recorded. Particularly, therelative birth rate and the health status of the newborn for each oocytewill be recorded and the gene expression levels of cumulus cellsassociated with each oocyte assessed as a function of pregnancy rate,newborn health, among other parameters, e.g., gender. Based on theseresults, a set of genes the expression of which correlates topregnancy/health outcome or gender will be identified. (“pregnancysignature”)

This set of genes, and the corresponding expression levels is referredto herein as the “pregnancy signature” because these gene expressionlevels correlate to the development of a viable pregnancy and ultimatelythe production of a healthy newborn. While this “pregnancy signature”may comprise as many as 50, 100 or even 200 genes, it is anticipatedthat a fewer number of genes, e.g., on the order of 20 or less genes,may be sufficient to develop a suitable “pregnancy signature”.

The genes which constitute the “pregnancy signature” may include geneswhich encode gene products that are involved in the nutritional anddevelopmental requirements of the oocyte, i.e., maturation anddevelopment, and the potential of the oocyte to be capable of yielding aviable pregnancy. These gene products may include growth factors,hormones, transcription factors, differentiation promoting agents, andthe like. After the “pregnancy signature” is obtained, the correspondinggenes are sequenced, the DNA sequences are then used to deduce theidentify the corresponding polypeptide sequences, and these sequencesthen compared to databases of available human or other gene sequences toidentify the identity of the gene products that correlate to the abilityof an oocyte to yield a viable pregnancy. Genes which are differentiallyexpressed by human oocytes are identified infra and include suchpregnancy signature genes. Further statistical analysis of the relativelevels of expression of these genes, or subsets of such genes, willidentify preferred subsets of these genes that constitute a “pregnancysignature” of a viable oocyte, i.e., one that is pregnancy competent.Some genes found to be differentially expressed in cumulus cells arecontained in SEQ ID NO's 1-513 infra. Additionally, FIG. 19 contains thesequences of three genes which are differentially expressed andexpressed at different levels in human cumulus cells associated withoocytes that give rise to viable pregnancies versus cumulus cellsassociated with oocytes that do not give rise to viable pregnancies.These three genes are the human arginine methyltransferase gene (PRMT5)and its transcript variants and other allelic variants, the human geneidentified in FIG. 19 as Clone IMAGE 5299642 and contained in depositedNCBI Accession Sequence BC041913; ACTB, and human BTG family member,member 2, BTG2, and contained in deposited NCBI Accession SequenceNM_(—)006763. The results of the gene expression experiments containedin Example 3 suggest that these 3 genes are all expressed at detectablyhigher amounts in cumulus cells that are associated with oocytes thatgive rise to viable pregnancies versus those that do not. While theexpression results are qualitative and have not yet been quantified thequalitative results would reasonably suggest that these genes are allexpressed at levels which are least 2-3 fold greater in cumulus cellsassociated with oocytes that give rise to viable pregnancies, and likelyup to 5-10-fold greater. Therefore, detecting the expression of thesegenes by cumulus cells derived from different donor ooytes, e.g., thoseto be used in an IVF procedure may be used as one means of predictingthe pregnancy potential of the oocytes associated therewith, i.e.,cumulus cells with higher levels of expression of these genes are morelikely to be associated with oocytes useful in IVF procedures.Therefore, these genes may be used as part of the pregnancy signatureset of genes the expression of which is assayed in order to assess thepregnancy potential of oocytes from a donor, e.g., a patient who iscontemplating being an IVF donor. Also, these gene expression proceduresmay be used to assess the pregnancy potential of oocytes in anindividual who is undergoing fertility treatments, an individual who isnear menopause (perimenopause), or an individual who has or had adisease or condition or treatment that potentially would impact theviability and quality of her oocytes such as radiation or chemotherapy.

As noted previously, these polypeptide gene products which are found tobe deficient in pregnancy incompetent oocytes may be added to in vitroculture media containing oocytes in order to enhance their pregnancycompetency or alternatively may be administered in vivo as part of afertility treatment regimen.

EXAMPLE 1 Exemplification of CRL Amplification Protocol of the Inventionwith Oocyte and ES Cell Samples

Oocte Collection, Total RNA Extraction and Reference RNA

Human oocytes were obtained from 3 patients undergoing an assistedreproductive treatment (ART) at the unit of Reproductive Medicine atClinica Las Condes, Santiago Chile. The selection criteria for thedonors was a) less than 35 years old, (b) reproductively healthy withregular ovulatory cycles; (c) male factor as the only cause ofinfertility, (d) considerable number of developing follicles thatassured spared oocytes. The experimental protocol was reviewed andapproved by a local independent Ethics Review Board. All donors signedinformed consent. At the time of this application filing, all threedonors had already conceived, two of them got pregnant during the ARTcycle in which the samples were collected, and the third one gotpregnant following a spontaneous cycle with artificial inseminationusing donated sperm. Ovarian stimulation and oocyte retrieval andisolation were performed as described herein.

Three groups of 10 oocytes were used. Total RNA was isolated followingthe guanidium thiocyanate method (28) using the PicoPure RNA isolationkit(Arcturus, CA) following manufacturer's instructions except only 6.6micromolar elution buffer was used and the elution was repeated at least3 times using the first eluate. All RNA samples within the purificationcolumn were treated with the Rnase-Free Dnase (Qiagen, CA). ExtractedRNA was stored at −80 degrees C. until used as a template for cDNAsynthesis. The quality and quantity of extracted total RNA from 8matured oocytes (independent from the 30 oocytes used in thisexperimental study(was evaluated using the Agilent 2100 bioanalyzer(Agilent Technologies, CA). Each mature oocyte was found to have about330 pg total RNA when the Arcturus' RNA isolation kit was used. Qualityof RNA was intact as shown in FIG. 3. Reference RNA (100 micrograms) wasprepared by mixing 10 micrograms total RNA from each of 10 differentnormal human tissues including skeletal muscle, kidney, lung, colon,liver, spleen, breast, brain, heart and stomach (Ambion, TX).

RNA Amplification for GeneChip Analysis (FIG. 4 a)

First-strand cDNA synthesis: the following reagents were added to eachof 0.5 ml Rnase-free tube: 5 micromolar total RNA (3 ng for thereference and 5 microliters, about 3 ng, for the oocyte samples) and 300ng of an anchored T7-Oligo(dT)24 V promoter primer (Ambion TX). Thereaction tubes were incubated in preheated PCR machine at 70 degrees C.for 2 min and transferred to ice. After denaturation, the followingreagents were added to each tube: 1.4 microliters of SMART II Aoligonucleotide (5′-AAGCAGTGGTATCAACGCAGAGTACGCGrGrGr-3″) (Clonetech,CA), 4 microliters of 5× first-strand buffer, 2 microliters of 20 mmDTT, 0.6 microliters of 5 mg/ml T4 Gene 32 Protein (Roche, IN), 2microliters of 10 mM dNTPs, 20 U Rnase inhibitor (Ambion, TX) and 1microliter PowerScript Reverse Trasnscriptase (Clontech, CA). Aftergentle mixing, reaction tubes were incubated at 42 degrees C. for 60minutes in a hot-lid thermal cycler. The reaction was terminated byheating at 70 degrees C. for 15 minutes and purified by NucleoSpinExtraction Kit (Clontech, CA).

Double-stranded cDNA synthesis by Long-distance (LD)-PCR, cDNApurification: PCR Advantage 2 mix (9 microliters) was prepared asfollows: 5 microliters of 10×PCR Advantage buffer (Clontech, CA), 1microliter of 10 mM dNTPs, 100 ng 5′ SMART upper primer(5′-AAGCAGTGGTATCAACGCAGAGTA-3′), 100 ng 3′ SMART lower primer(5′-CGGTAATACGACTCACTATAGGGAGAA-3′), and 1 microliter of Polymerase MixAdvantage 2 (clontech, CA). This mix was added to 41 microliters of thefirst-strand cFDNA synthesis product, and thermal cycling was carriedout in the following conditions: 95 degrees C. for 1 minute, followed by15 cycles, each consisting of denaturation at 94 degrees C. for 30 sec,annealing at 62 degrees for 30 sec, and extension at 68 degrees C. for10 min. The cDNA was purified by NucleoSpin Extraction Kit following themanufacturer's instructions.

In vitro transcription (IVT), biotin labeled aRNA purification and aRNAfragmentation is described herein.

Microarray Analysis: Transcription profile of each sample was probedusing Affymetrix Human Genome U133 Plus 2.0 GeneChips. The raw dataobtained after scanning the arrays was analyzed by dChip (29). Asmoothing spline normalization method was applied prior to obtainingmodel-based gene expression indices, a.k.a. signal values. There were nooutliers identified by dChip so all samples were carried on forsubsequent analysis.

Pathway analysis was performed using Ingenuity Software Knowledge Base(Redwood City, Calif.) which is a manually created database ofpreviously published findings on mammalian biology from the publicliterature. We used the network analysis using the knowledge base toidentify interactions of input genes within the context of knownbiological pathways.

Gene ontology (GO) was performed using EASE. Given a list of genes, EASEforms subgroups based on the functional categories assigned to eachgene. EASE assigns a significance level (EASE score) to the functionalcategory based on the probability of seeing the number of subgroup geneswithin a category given the frequency of genes fro that categoryappearing on that microarray (30)

Comparison with External Data Sets

MouseMII oocyte transcriptome data was obtained from Su et al., who usedcustom designed Affymetrix chips to obtain gene expression profiles ofoocytes and 60 other mouse tissue types. (31) Using their expressiondatabase we identified 3,617 differentially upregulated transcripts inthe mouse oocyte by using the median expression value of the remaining60 samples as the baseline (Supplementary dataset 1, not shown). Weselected transcripts with an expression value in oocyte samples that are2-fold higher than the base-line.

Human embryonic stem cell (hESC) data was derived from the work of Satoet al. who profiled human stem cells and their differentiatedcounterparts using Affymetrix HG-U133A representing around 2200transcripts. (32)

We analyzed raw data using dChip and identified 1,626 hESC genes byselecting transcripts significantly upregulated in human stem cellscompared to their differentiated counterparts (Supplementary dataset 2,not shown).

Finally for mouse ES cells we used a list of 1,687 differentiallyupregulated mouse ES genes published by Fortunel et al (33) which wereidentified by comparing mouse ES cells to differentiated cells usingAffymetrix MG-U74Av2 chips representing around 1200 transcripts(Supplementary dataset 3, not shown). We used Affymetrix NetAfffx toolfor mapping genes across organisms and platforms used in the respectivestudies.

RESULTS AND CONCLUSIONS

Validation of amplification Fidelity (Amplified vs. non-amplified RNA)

A critical step in the analysis of gene expression on small samples isthe faithful amplification of mRNA molecules present in the sample. Wehave designed a PCR based amplification system using the combination ofSMART UII A oligonucleotide (Clontech, CA) and T7-Oligo (dT) promoterprimers (“CRL amplification protocol”). (FIG. 3 a) We have isolatedtotal RNA from a human cell line and 20, 3 and 1.5 ng input total RNAwas amplified using CRL amplification protocol. For each experiment, 15micrograms of fragmented aRNA was hybridized to a single AffymetrixHuman Genome U133 Plus 2.0 array. Non-amplified RNA from the originalsample (12 micrograms) was run in parallel by using the MessageAmp IIaRNA Kit (Ambion, TX). Gene expression results from both amplified vsnon-amplified RNA samples were compared and the correlation coefficientswere found to be 0.94. (FIGS. 3 b), 0.03, and 0.91 respectively for 20ng, 3 ng, and 1.5 ng of total input RNA respectively. CRL amplificationprotocol was repeated two times with 20 ng initial total RNA from thesame cell type and the correlation between the two experiments was 0.99,These results show that the subject RNA amplification strategyfaithfully and consistently amplifies even small amounts of RNA toquantities required to perform microarray experiments. The CRLamplification protocol provides a practical approach to facilitate theanalysis of gene expression in samples of small quantity whilemaintaining the relative gene expression profile throughout reactions.

Differentially Upregulated Genes in the Human Oocyte

We generated a databases of the human oocyte transcriptome by comparingthe transcripts in the oocyte and the reference samples which containmRNA from several somatic tissues. A complete list of up and downregulated genes, functional comparative and correlation analysis isprovided (see Supplementary dataset 4). Compared to reference samplesthere were 5,331 transcripts significantly up-regulated and 7,074transcripts significantly down-regulated in the oocyte. Genesup-regulated in oocyte samples included most of the well-known germ cellspecific genes, such as FLGLA, STELLA, VASA, DAZL, GDF9, ZP1, ZP2, MOS,OCT4, NPM2, and H1F00. (FIG. 4), Our analysis also confirms the presenceof pathways previously described in the mouse, in particular theTGF-beta pathway (FIG. 5)

Validation of microarray data

A selected list of genes known to be expressed in the oocyte was used tovalidate the microarray results by TR-PCR (FIG. 4). These genes werefound to be present in the oocyte sample and absent in the referenceRNA.

Functional Annotation of Genes Over-Expressed in the Human Oocyte

To examine the biological processes performed by the oocyte, weimplemented EASE (36), contrasting the genes over-expressed in theoocyte with all the genes present in the Affymetrix chip (Table 1). Oneof the top over-represented categories found in oocytes was related toRNA metabolism. This is in agreement with the fact that oocytes storeRNA to support the events of fertilization and early embryonicdevelopment until the embryonic gene is activated. (34,35,36) DNAmetabolism and chromatin modification were also over-representedcategories, in agreement with the need of the oocyte to remodel thesperm chromatin upon fertilization.

Cell cycle related categories were the most over-represented. Many genesknown to be involved in the regulation of the meiotic cell cycle Manygenes known to be involved in the regulation of the meiotic cell cyclewere detected (MOS, AKT2, CDC25, and PLK1) (37) Detection ofgametogenesis and reproduction as over-represented categories furthersuggests the accuracy of this transcriptional profiling. Protein kinasesand phosphatases denoted another functional category over-represented inoocytes. Many of the cell cycle regulatory genes (AURKB, CDC25, DCD7,PLK1, CDC23 and plk3) and some receptors of the TGF superfamily (ACVR1,ACVR2B, and BMPR1A and 1B) were in this category.

An important category that is highly represented in the oocyte wasrelated to nucleic acid metabolism and regulation of transcription.Although transcriptionally silent at the MII stage, the oocyte is veryactive in transcription and translation during its growth phase and mustbe prepared to initiate transcription at the time of embryonic genomeactivation, 4- to 8-cell stage in human (38). Many of the genes in thiscategory represent Zinc0-finger proteins that are not yet fullycharacterized, providing an opportunity to discover new transcriptionalregulatory networks that operate during embryonic genome activation.

We also found that chromatin remodeling genes are well represented inthe human oocyte. Genes in this category expressed in the human oocytewere: DNA methyltransferases (DNMT1, DNMT3a, and DNMT3B), histoneacetyltransferases (NCOA1,and 3, SRCAP, GCN5L2 and TADA2L), histonedeacetyltransferases (HDAC3 HDAC9, SIRT7), methyl-CpG-binding proteins(MBD2 and MBD4), histone methyltransferases (EHMT1 and SET8),ATP-dependent remodeling complexes (SMARCA1, SMARCA5, SMARCAD1, SMARCC2,SMARCD!) and other chromatin modifying genes (ESR1, NCOA6, HMGB3, HMGN1and HMGA1).

These GO results validate our transcriptome analysis when compared withcandidate gene analysis already reported in other species but moreimportantly, shed new light into a large number of biological processesthat take place in the human oocyte.

Intersection Between Human Oocyte and Mouse Oocyte Transcriptome

Mouse has been the best model for genetic studies and several groupshave already reported the transcriptome analysis of mouse oocytes.(39)In an effort to find differences and similarities between the human andmouse oocyte, we compared our human oocyte transcriptome results withthat of mouse oocyte transcriptome derived from, data of Su et al. (35)The intersection of the two transcriptomes yielded a set of 1587 genesto be common in both mouse and human oocytes, indicating genes ofconserved function in mammalian oocytes (FIG. 6 a, Supplementary dataset5). Table S2 shows the functional characterization of 16 of the top 100intersected genes which have functions described in mouse oocytes. Manyof these genes relate to oocyte maturation, from the first meioticdivision to MII arrest, encompassing various controls of cell cyclecheckpoints and cellular machinery for DNA segregation and celldivision. Using the Ingenuity software to analyze the intersection ofthese two datasets we found that the estrogen receptor (ER) signalingpathway is represented in human and mouse oocytes (FIG. 6) Genessignificantly upregulated in this pathway were CTBP2, ESR1, GTFH1,GTF2H2, MAP2K1, NCOA1, NCOA3, PCQAP, PHB2, POLR2C, POLR2J, RBM9, TAF3,TAF4, TAF4B, TAF5, TAF6, TAF12, and TBP. Recent studies in knockoutmodels for aromatase have shown that estrogen is not required for thegeneration of preimplantation embryos. (40) However, our study suggeststhat in the oocyte some genes associated with the ER pathways aretranscribed, perhaps in response to hormonal stimulation duringfolliculogenesis and oocyte maturation. Like with the EGF pathway, itremains to be determined whether the ER pathway has a role duringpreimplantation development in human embryos.

Considering the high degree of similarity

EXAMPLE 2 Description

Phase I: At the clinic, embryologists will remove the cumulus cells oftwo eggs and fertilize them. Embryos will be transferred to the uterusof a woman and cumulus cells sent to the laboratory for analysis. Oncethe cells arrive to the laboratory, RNA will be isolated and microarrayanalysis performed using Affymetrix platform. Pregnancy tests will bedone by ultrasound on day 30 and embryonic sacs counted. There will bethree kinds of outcomes. 1) 0 sacs; 2) 1 sac and 3) 2 sacs. A minimum of30 volunteer women will participate during this phase. Ten with no sacs,ten with one sac and ten with 2 sacs. Pregnancy data will be correlatedwith gene expression obtained from the cumulus cells isolated from thosesame eggs. One hundred genes that directly correlate withpregnancy—either by upregulation or downregulation—will be furtheranalyzed using real time RT-PCR. The best 20 genes that correlate withpregnancy (positively or negatively) will be called “pregnancysignature” and used for later testing at the clinic.

Phase II: Blind validation of genes in the pregnancy signature. At theclinic, the embryologist will isolate RNA from cumulus cells from eachoocyte that will be later fertilized. Half of the RNA will be sent toour laboratory and the rest will be used for real time RT-PCR analysisto be performed on site. Gene expression of the “pregnancy signature”will be measured. Embryologists will transfer embryos without knowingthe outcome of gene expression analysis. One hundred women will be askedto participate as volunteers in this part of the study. At the timepregnancy results are obtained, the study will be unmasked and resultsfrom each individual will be correlated with gene expression analysis.We anticipate that the “pregnancy signature” put forward in phase 1 willbe validated during this phase.

Alternative strategy: In the event of an unexpected outcome i.e., thepregnancy signature is not validated; microarray analysis will be runonce more using the RNA provided by the clinic in phase 2. It isanticipated that having 100 more samples will result in theidentification of a clear pattern of gene expression in cumulus cellsfrom eggs capable (or non-capable) of generating a healthypregnancy/baby.

Using microarray analysis as described above, the genes identified infrawere found to be differentially expressed by cumulus cells obtained fromeggs of women donors. The expression of those particular genes whichcorrelate to pregnancy (positive or negative) will establish a“pregnancy signature”, i.e., genes the expression or absence ofexpression of which correlates to a positive pregnancy outcome and“infertility signature”, i.e., specific genes the expression or absenceof expression correlate to fertility problems or abnormalities.

This is effected preferably by microarray analysis. For example,comparison of expression between two samples on filter arrays may beperformed by comparing nucleic acids obtained from normal oocyte cellsto those obtained from a donor suspected of having ovarian dysfunctionthat renders oocytes pregnancy incompetent on two duplicate filters oralternatively a single filter may be used that is stripped andhybridized sequentially.

Direct comparison of gene expression in two samples can be achieved onglass arrays by labeling the two samples with different flourophores.This technique allows the evolution of repression of gene expression aswell as induction of expression. The two flouresently-labeled cDNAs arethen mixed and hybridized on a single glass or filter array. Glassarrays have the advantage of allowing the simultaneous analysis of twosamples on the same array under the same hybridization conditions.

Gene arrays containing sequences of genes implicated in pregnancy(“pregnancy signature”) will allow high-throughput screening ofindividuals for diagnostic purposes or tailor-made treatments.

Arrays of polynucleotides, the expression of which corresponds to, orare complementary to the sequences of genes identified by the method ofthe invention therefore provide a further aspect of the invention. Suchan array will include at least two nucleic acid sequences, preferably atleast 10, and more preferably at least 20, e.g., 50 genes or more thatcorrespond to the sequence of, or are complementary to genes, theexpression of which (positive or negative) the positive pregnancyoutcome in cells obtained from oocyte donors, e.g., women suspected tohave ovarian dysfunction as a result of disease, age, and the like.Protein arrays form a further aspect of the invention and will containpolypeptides encoded by such pregnancy signature genes or antibodieswhich bind thereto.

Recent developments in the field of protein and antibody arrays allowthe simultaneous detection of a large number of proteins.

EXAMPLE 3 Identification of 3 Pregnancy Signature Genes Which AreDifferentially Expressed by Cumulus Cells and Wherein The ExpressionLevels of Which Correlate to Pregnancy Outcome of Associated HumanOocytes

There are no prior reports describing correlations between overall geneexpression in cumulus cells and pregnancy establishment of humanembryos. A study essentially as described in Example 2 was conducted toidentify differentially expressed genes between cumulus cellssurrounding competent and noncompetent oocytes using Affymetrix GeneChiptechnology. To achieve this goal cumulus cells were classified accordingto pregnancy outcome of their matching oocytes following in vitrofertilization (IVF) treatments. The cumulus cells from 2 oocytes perpatient undergoing IVF treatment were lysed and the oocytes werefertilized and transferred to the recipient women, 2 embryos perrecipient with the exception of 2 that received a single embryo. TotalRNA isolated from the cumulus cell lysates was amplified by the novelamplification protocol described supra that combined template-switchingPCR and T7-based amplification methods. A total of 52 cumulus cellsamples were analyzed from 27 donors (FIG. 12). A gene-by-gene mixturemodel analysis was used to compare microarray measurements of geneexpression on cumulus cells between pregnant and non-pregnant patients.2,604 differentially expressed genes were considered as potentialdiscriminant candidates of competent and noncompetent oocytes.

A flow chart of the specific procedures used is contained in FIG. 13which shows how the quality and quantity of total RNA from differentcumulus cell lysates is verified. The Experimental Design is alsodepicted schematically in FIG. 14 and the CRL amplification protocol anda scatter plot of the obtained results by the CRL amplification versusanother method (Ambion) is contained in FIG. 15.

As shown in FIG. 16 a comparison of the differential expression profilesof genes by cumulus cells of oocytes that give rise to pregnancies from4 pregnant donor samples versus 4 donor samples that did not give riseto pregnancy reveals a clustering of samples using genes that are calledpresent on the 4 pregnancy donor samples and 4 non-pregnant donorsamples (442 probe sets).

FIG. 17 contains the expression patterns of 3 candidate pregnancy markergenes in cumulus cells that produced pregnancy versus non-pregnancy.Additionally, FIG. 18 contains a Table containing the top 10 functionalgene categories overrepresented in differentially expressed genesbetween cumulus cells emanating from oocytes that produce pregnanciesversus those that failed to produce pregnancies. Gene ontology andbiological process and molecular function as detected by EASE whenoocyte expressed genes were compared to the genes represented in theGeneChip array.

These results provide the first known comprehensive expression baseline(transcriptome) for the genes which are expressed in the human cumuluscells that surround a pregnancy-competent oocyte. As discussed, thesegenes may serve as markers for the quality and pregnancy outcome of theoocyte and can be used to monitor and optimize the factors that arerelated to developmental competence, such as patient specific medicaltreatments and medical conditions, hormone treatments, and embryoculture conditions. In addition, the effective development of pregnancymarkers such as the genes which are contained in FIG. 19 can increasethe probability of a healthy pregnancy and viable birth; reduce thechances of multiple births, physical and emotional burden, and the costsin treatments and hospital stays. Additionally, identifying these genesmay facilitate an understanding of the underlying biology and helpexplain how the levels of expression of these genes may impact or causefemale infertility.

Lengthy table referenced here US20110244464A1-20111006-T00001 Pleaserefer to the end of the specification for access instructions.

LENGTHY TABLES The patent application contains a lengthy table section.A copy of the table is available in electronic form from the USPTO website(http://seqdata.uspto.gov/?pageRequest=docDetail&DocID=US20110244464A1).An electronic copy of the table will also be available from the USPTOupon request and payment of the fee set forth in 37 CFR 1.19(b)(3).

1-45. (canceled)
 46. A method of identifying oocytes that are capable ofgiving rise to a viable pregnancy when fertilized comprising thefollowing steps: (i) obtaining at least one cumulus cell associated withan oocyte; (ii) assaying the expression of at least 5 genes selectedfrom the genes in Table 1, wherein at least 2 of said genes are selectedHAS2, PTX3, DHFR, ZNF93, DUSP12, STK35, WTAP, AQP3 by said at least oneoocyte associated cell, the expression of which correlates to thecapability of an oocyte associated with said cell to yield a viablepregnancy upon fertilization and transferral into a suitable uterineenvironment; and (iii) identifying, based on the level of expression ofsaid at least one gene, whether said oocytes is potentially capable ofyielding a viable pregnancy upon fertilization and transferral into asuitable uterine environment.
 47. The method of claim 46, wherein saidoocyte is a mammalian oocyte.
 48. The method of claim 47, wherein saidoocytes is a human oocyte.
 49. The method of claim 47, wherein saidoocyte is a non-human primate oocyte.
 50. The method of claim 46,wherein the expression of at least 10 genes, the expression of whichcorrelates to the capability of an oocyte to potentially yield a viablepregnancy are identified.
 51. The method of claim 46 wherein said atleast one gene additionally includes at least one gene selected from thegroup consisting of PRMT5, PTG2, ACTB, or a variant thereof possessingat least 95% sequence identity to one of the sequences contained in FIG.19.
 52. The method of claim 46, wherein the expression of at least 15genes, the expression of which correlates to the capability of an oocyteto potentially yield a viable pregnancy are measured.
 53. The method ofclaim 46, wherein the expression of at least 20 genes, the expression ofwhich correlates to the capability of an oocyte to potentially yield aviable pregnancy are identified.
 54. The method of claim 53, wherein theexpression of at least 20 to 50 genes, the expression of whichcorrelates to the capability of an oocyte to potentially yield a viablepregnancy are identified.
 55. The method of claim 54, wherein theexpression of at least 50 to 100 genes, the expression of whichcorrelates to the capability of an oocyte to potentially yield a viablepregnancy are identified.
 56. The method of claim 46 wherein the methodof assaying gene expression uses a method that monitors differentialgene expression.
 57. The method of claim 56 wherein said methodcomprises indexing differential display reverse transcriptase polymerasechain reaction (DDRT-PCR).